1. Field of the Invention
The present invention relates to an image forming apparatus, such as a copier and a printer, that forms an image on a recording material, using an electro-photographic technique.
2. Description of the Related Art
As a fixing apparatus included in an image forming apparatus using the electro-photographic technique, a fixing apparatus that uses a cylindrical film is known. This fixing apparatus has a film, a heater that contacts the inner surface of the film, and a pressure roller that constitute a nip portion, together with the heater via the film. The fixing apparatus heats the recording material bearing a toner image using the nip portion, so as to fix the toner image to the recording material.
A merit of this fixing apparatus is that the warm-up time of the apparatus is short, since the heat capacity of the members of the apparatus, including the heater and the film, is low. Because of this effect, the time from the apparatus receiving a print signal to completing the printing of the first sheet (FPOT: First Print Out Time) can be decreased. Power consumption can also be reduced since it is unnecessary to supply power to the heater while waiting for reception of the print signal.
On the other hand, it is known that in the fixing apparatus that uses this film, temperature in a non-paper passing portion easily rises, and an apparatus that can more effectively control this temperature rising in the non-paper passing portion is demanded.
To meet this demand, a configuration of blowing a breeze from a fan onto the fixing film of the non-paper passing portion and onto the pressure roller was proposed (Japanese Patent Application Laid-open No. 2007-187816).
With the above configuration, however, it is inevitable that the apparatus will become larger and cost will increase.
A countermeasure to the temperature rising in the non-paper passing portion is to reduce the caloric value of the heater in the non-paper passing portion. However, if the caloric value of the heater in the non-paper passing portion is reduced, the toner image in the end portion may not be sufficiently fixed, which generates a defective image.